1. Field of the Invention
The present invention relates to an ink jet recording apparatus and method and, more particularly, to an ink jet recording apparatus and method to prevent the occurrence of band unevenness and deterioration of a recording speed, caused by a color image and a black image mixedly existing in a recorded area.
2. Related Background Art
An ink jet recording method has been broadly used for printers and copying machines because of the realization of a low noise, a low running cost, a small size and ease of color printing of a recorded image.
In an apparatus utilizing such an ink jet recording method, four color inksxe2x80x94black, yellow, cyan, and magentaxe2x80x94are generally used for color image recording. In addition, there has been put into practical use an apparatus capable of recording a high-quality color image having a less conspicuous granular appearance by using inks of light-black, light-yellow, light-cyan, and light-magentaxe2x80x94obtained by reducing the ink densities of the above four colorsxe2x80x94in addition to the four colors.
In such color ink jet recording apparatuses, in order to realize both a high processing speed upon printing black characters and low cost of the recording apparatus, there has been proposed a method wherein the number of discharging orifices in the black ink recording head is greater than that of the other color ink recording heads. Providing many discharging orifices in the black ink recording head realizes the high-speed recording of black characters. As the length of the head increases, the cost rises. Decreasing the number of discharging orifices in the color ink recording heads reduces the length of each head, so that the costs of heads decrease. Consequently, a lower cost of the whole recording apparatus is realized. Generally, in a serial printer, the discharging orifice array of the black ink recording head and the discharging orifice arrays of the color ink recording heads are arranged in parallel so as to be parallel with the direction perpendicular to a main-scanning direction for recording.
In an ink jet recording apparatus comprising heads with a different number of discharging orifices for each color, an area to be recorded with a black ink and a color ink superposed, and an area to be recorded in one main-scanning and an area to be recorded in the other main-scanning may mixedly exist. This occurs by using the heads with the different number of discharging orifices for colors. Furthermore, an area which can be recorded with the black ink but cannot be recorded with the color ink appears in one main-scanning at the time of the main-scanning of the head.
Ordinarily, in the case of recording with two color inks superposed, the color tone changes depending on the difference between the recording timings of two color inks. It is estimated as follows. When comparing the case where the following ink droplet reaches the recording medium before the preceding ink droplet has penetrated enough into the recording medium with the case where the following ink droplet reaches the recording medium after the preceding ink droplet has penetrated enough into the recording medium, the rate of penetration of the preceding ink droplet into the recording medium in the former case is different from that in the latter case. The difference between the penetration rates results in a difference between the tones in portions where two color inks have been superposed. As mentioned above, when the area recorded with two color inks is superposed or combined in the same main-scanning and the area recorded with two color inks superposed in the other main-scanning mixedly exist, so-called lateral-striped band unevenness occurs. Hitherto, in the above-mentioned ink jet recording apparatus, it is a problem that band unevenness occurs.
Hitherto, in order to avoid the problem, there has been proposed a method of recording in such a manner that a high picture quality recording mode is performed. In the recording mode, not all of the discharging orifices of the black ink recording head are used, but only the discharging orifices of the black ink recording head which correspond to an area capable of being recorded by the color ink recording heads in the same main-scanning are used to record. In other words, it is a method wherein the number of discharging orifices of the color ink recording heads to be used is equal to that of the black ink recording head and the number of discharging orifices for black is set so as to be equal to that of the color ink recording heads.
However, in the conventional high picture quality recording mode, when any color image exists in a recording area, not all of the discharging orifices of the black ink recording head are used even when black images occupy most of the recording area. Consequently, when a predetermined recording area for the black images alone is recorded, it is a problem that recording speed is remarkably deteriorated.
The present invention is made in consideration of the above problems. According to the present invention, it is an object to provide an ink jet recording apparatus and method wherein upon recording using heads with different numbers of discharging orifices for colors, even when a color image and a black image mixedly exist in a recording area, the occurrence of band unevenness is suppressed without deteriorating a recording speed.
In order to accomplish the above object, a recording apparatus according to the present invention is characterized by comprising as follows.
That is, there is provided an ink jet recording apparatus for recording an image on a recording medium, wherein a first discharging orifice array arranging a plurality of discharging orifices for discharging a first ink and a second discharging orifice array arranging a plurality of discharging orifices for discharging a second ink are disposed in parallel in a main-scanning direction different from the arranging direction, and the first discharging orifice array, second discharging orifice array, and recording medium are relatively moved in the arranging direction of the discharging orifices for each main-scanning of the first and second discharging orifice arrays in the main-scanning direction, and wherein when it is assumed in one main-scanning that an area where a main-scanning area of the first discharging orifice array does not overlap with a main-scanning area of the second discharging orifice array is set to a first area and an overlapping area is set to a second area, in the case where image data to be recorded by the second discharging orifice array exists in the first area, recording for the first area by the first discharging orifice array is not performed, and in the case where no image data to be recorded by the second discharging orifice array exists in the first area, recording for the first area is performed by the first discharging orifice array.
A recording method according to the present invention is characterized by comprising as follows.
That is, there is provided an ink jet recording method of recording an image on a recording medium in such a manner that a first discharging orifice array arranging a plurality of discharging orifices for discharging a first ink and a second discharging orifice array arranging a plurality of discharging orifices for discharging a second ink are disposed in parallel in a main-scanning direction different from the arranging direction, and the first discharging orifice array, second discharging orifice array, and recording medium are relatively moved in the arranging direction of the discharging orifices for each main-scanning of the first and second discharging orifice arrays in the main-scanning direction, wherein when it is assumed in one main-scanning that an area where a main-scanning area of the first discharging orifice array does not overlap with a main-scanning area of the second discharging orifice array is set to a first area and an overlapping area is set to a second area, in the case where recording by the first discharging orifice array and recording by the second discharging orifice array are performed in the first area, the recording by the first discharging orifice array and the recording by the second discharging orifice array are performed in the same main-scanning.
A computer readable storage medium according to the invention is characterized by comprising as follows.
There is provided a computer readable storage medium which has stored a program code to execute a recording control process of an ink jet recording apparatus for recording an image on a recording medium in such a manner that a first discharging orifice array arranging a plurality of discharging orifices for discharging a first ink and a second discharging orifice array arranging a plurality of discharging orifices for discharging a second ink are disposed in parallel in a main-scanning direction different from the arranging direction, and the first discharging orifice array, second discharging orifice array, and recording medium are relatively moved in the arranging direction of the discharging orifices for each main-scanning of the first discharging orifice array and second discharging orifice array in the main-scanning direction, wherein the program code includes control processing codes to control the ink jet recording apparatus in such a manner that when it is assumed in one main-scanning that an area where a main-scanning area of the first discharging orifice array does not overlap with a main-scanning area of the second discharging orifice array is set to a first area and an overlapping area is set to a second area, in the case where image data to be recorded by the first discharging orifice array and image data to be recorded by the second discharging orifice array exist in the first area, recording for the first area by the first discharging orifice array is not performed in the main-scanning, and in the case where image data alone to be recorded by the first discharging orifice array exists in the first area and no image data to be recorded by the second discharging orifice array exists, recording for the first area is performed in the main-scanning by the first discharging orifice array.